The present invention relates to inhibiting the antagonism between pyridyloxy-phenoxy alkanoate herbicides and benzothiadiazinone herbicides when applied post-emergently in compositions containing both classes of herbicides.
Pyridyloxy-phenoxy alkanoate derivatives, such as, for example, those described in Belgium Pat. No. 868,875; PCT Application WP No. 7900094; EPO Application No. 483; U.S. Pat. No. 4,213,774; and French Pat. No. 7522436, are useful as herbicides and are especially effective for selectively controlling annual and perennial grassy weeds in the presence of desirable broadleaf plants.
Benzothiadiazinone derivatives, described in U.S. Pat. Nos. 4,015,130; 4,116,672; 4,155,746; 3,940,389; 3,708,277 and 3,621,017 are useful as herbicides and especially as broadleaf active herbicides.
Pyridyloxy-phenoxy alkanoate herbicides are typically applied post-emergently in the presence of nonionic surfactants. To extend the weed control spectrum in a given application, pyridyloxy-phenoxy alkanoate herbicides are mixed with benzothiadiazinone broadleaf active herbicides and thereafter applied to unwanted vegetation as a broad spectrum herbicidal composition effective against grasses and broadleaf weeds. The herbicidal activity to grasses of such mixtures is less than when pyridyloxy-phenoxy alkanoate herbicides are applied alone. Because of this antagonism in activity, it is necessary to increase the amount of the pyridyloxy-phenoxy alkanoate component in such mixtures to obtain equivalent grass control comparable to lesser amounts of pyridyloxy-phenoxy alkanoates when applied alone.
It is, therefore, desirable to provide a method for inhibiting the antagonism between pyridyloxy-phenoxy alkanoate herbicides and benzothiadiazinone herbicides when such herbicides are combined for post-emergent application to undesirable vegetation.